GB126970A - Improvements in or relating to Reproducing Apparatus for use with Phonographs and other Talking Machines. - Google Patents

Abstract

126,970. Soc. Anon. des Etablissements Gaumont. May 17, 1918, [Convention date]. Magnetic instruments. - An electro-magnetic reproducer for phonographs &c. comprises a magnetic blade connected to the stylus arm and vibrating between the poles of a magnet, the blade being surrounded by a coil connected to a telephone receiver preferably through a relay. The stylus arm 3 is horizontally pivoted to a vertical post 14 turning in a socket 15. The magnetic blade 1 is secured in a vertical position to the arm 3 preferably at a point three-quarters of the length of the arm away from the stylus 10. The upper end of the blade 1 is secured to an iron block 4 attached to the magnet 5 by screws 6, which are adjusted so that the magnet poles N, S are equidistant from the blade. A coil 9 surrounds the blade 1, and a frame 7 of non- magnetic material is clamped to the magnet by a screw 8, which also permits adjustment of the distance between the poles. When the blade 1 is in a central position, the magnet flux does not pass along the blade, but when the blade is vibrated to either side the flux is diverted along the blade, producing electromotive forces in the coil, 9, and causing the telephone receiver to emit sounds corresponding to the sounds recorded. Although the magnet 5 and frame 8 are supported on the arm 3, their inertia prevents them from following the vibrations of the arm. The natural period of oscillation of the magnet and frame mounted on the elastic blade should be greater than the period of the sounds to be reproduced.